Today we commemorate Martin Luther King Jr. Day with a look back at our civil rights heroes and the moments that defined a nation. March 7, 1965, aka “Bloody Sunday,” is an event remembered by our history textbooks as a violent climax in the Civil Rights Movement. In a new piece titled, “The Bridge to Freedom,” civil rights activist and Harvard law professor Lani Guiner reflects back on the march in Selma, Alabama as more than a tragedy, but as a tipping point in history; it was the spectacle that galvanized a nation to cry out, a president to act, and a bill to pass.

Guiner writes:

“Congress did not pass and President Lyndon Johnson did not sign the Civil Rights Act of 1964 and the Voting Rights Act of 1965 simply because it was the right thing to do. Both were pushed by a mass movement to guarantee civil rights for all. The success of that movement, to quote Martin Luther King Jr., ‘depended on ordinary people sending their message with ‘the blunt pen of marching ranks.’ Nowhere did these marchers sound clearer than in Selma, Alabama” (Time, 2014).